Fabrication of tetragonal square spiral photonic crystals

We present a simple, versatile technique for the fabrication of large, three-dimensional gap photonic crystals using glancing angle deposition (GLAD). A tetragonal lattice suitable for a large photonic band gap (PBG) can be synthesized by a regular array of square spiral structures grown from a simple, prepatterned substrate using physical vapor deposition and advanced substrate motion. Tetragonal square spiral crystals with a predicted PBG of up to 15% for a silicon structure can be produced in the visible, NIR, and IR spectrum. These PBG's exhibit good stability for large areas of parameter space that can be readily mapped out by the GLAD process through the variation of deposition parameters.